This invention relates to an improved fluid sampler device, and more particularly to an improved sampler having a novel two stage pump of the combined air lift and bladder pump variety.
There are currently available a variety of fluid sampling devices which incorporate a single stage pump for sampling groundwater and the like. By way of example, reference is made to U.S. Pat. No. 4,489,779, which discloses a sampler device that utilizes a single stage bladder pump in a well casing for purging and then withdrawing fluid samples from the well. For certain types of wells it has also been customary heretofore to support a bladder pump of this type in a well casing in side-by-side relation to a separate, air lift pump, which is used for purging stale well water from the casing, after which the bladder pump is operated to collect the desired samples.
One of the disadvantages of the devices which utilize both bladder and air lift pumps is that, by virtue of the fact that the bladder pump and air lift pump are mounted separately from one another, or side-by-side in a well casing, the cost of producing and controlling the two separate pumps is relatively high, and also requires that the diameter of the associated well casing into which they are inserted be at least large enough to accommodate the pumps in side-by-side relation. Moreover, depending upon the depth of the respective well into which such equipment is to be inserted, separate provisions must be made for extending the lengths of the fittings for each pump.
It is an object of this invention, therefore, to provide an improved sampler which utilizes a coaxially disposed two stage pump, which incorporates both an air lift pump and a bladder pump, in a single casing, thus enabling the sampler to be employed in relatively small diameter well casings, as compared to known samplers.
Still another object of this invention is to provide for samplers of the type described a novel two stage pump, which is relatively simple and inexpensive to manufacture, and which is readily extensible to suit various well depths.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.